Probability



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This is a photo taken of the night sky. A meteor and its tail are shown entering the earth's atmosphere.
Figure 3.1 Meteor showers are rare, but the probability of them occurring can be calculated. (credit: Navicore/flickr)

Chapter Objectives

By the end of this chapter, the student should be able to:

  • Understand and use the terminology of probability.
  • Determine whether two events are mutually exclusive and whether two events are independent.
  • Calculate probabilities using the Addition Rules and Multiplication
    Rules.
  • Construct and interpret Contingency Tables.
  • Construct and interpret Venn Diagrams.
  • Construct and interpret Tree Diagrams.

It is often necessary to “guess” about the outcome of an event in order to make a decision. Politicians study polls to guess their likelihood of winning an election. Teachers choose a particular course of study based on what they think students can comprehend. Doctors choose the treatments needed for various diseases based on their assessment of likely results. You may have visited a casino where people play games chosen because of the belief that the likelihood of winning is good. You may have chosen your course of study based on the probable availability of jobs.

You have, more than likely, used probability. In fact, you probably have an intuitive sense of probability. Probability deals with the chance of an event occurring. Whenever you weigh the odds of whether or not to do your homework or to study for an exam, you are using probability. In this chapter, you will learn how to solve probability problems using a systematic approach.

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